Interfacial properties pertinent to W/O and O/W emulsion systems prepared using polyaromatic compounds

Abstract

Establishing interfacial science to understand molecular mechanisms of stabilizing water in heavy crude oil (W/O) emulsions is challenging due to non-transparent nature of crude oil even in diluted systems, as most of the interfacial property measurements are based on visualization of the experimental systems. This study investigates whether interfacial properties measured using transparent O/W emulsion systems could be used to understand the stability of W/O emulsion systems. With the same chemistry of interfacially active polyaromatic compounds (C5Pe and C5PeC11) in xylene as the model oil, the interfacial tension, crumpling ratio, dilatational rheology and coalescence time of W/O and O/W systems were measured. For less surface active C5PeC11, the interfacial tensions for W/O and O/W systems were similar. For more surface active C5Pe, the interfacial tension of the W/O system was lower than that of the O/W system, while the film rigidity and viscoelasticity of the W/O system were higher than that of the O/W system. At low C5Pe concentration, the coalescence time for the W/O system was lower than that for the O/W system with the coalescence time for the W/O system being higher at higher C5Pe concentrations. The results reveal that even though the interfacial properties measured using reverse O/W system exhibit similar qualitative trends, care should be taken when quantitatively studying W/O emulsions using interfacial property measurements of the O/W system due to the difference in most of the interfacial properties measured using the W/O and O/W systems.